This issue was first introduced in 1.21.4 Pre-Release 3.

When you try to land on the edge of Powder Snow from over 2.5 blocks, you cannot continue to go down, and are instead constantly teleported back to the landing position.

In addition, if you manage to leave the edge, you will take full damage, unlike in previous versions.

Steps to reproduce

1. Place a powder snow
2. Fly directly above the edge of the powder snow, at least 2.5 blocks high
3. Fall down
   You get stuck at where you land on

Expected behavior

You would fall through the edge of the Powder Snow, just like in 1.21.4 Pre-Release 2 and before.

Additional notes

This issue may relate to MC-264553.